Recent Advances in Anionic Polymerization

Synthesis of well‐defined macrocyclic block copolymers using living coupling agent method

“…The 4-armed star block copolymer was prepared according to the procedure described in Ref. 5. The cyclization reaction of the dilithium &armed star block copolymer was the same as that described for the cyclic SB block copolymer using dimethyldichlorosilane as a coupling agent.…”

Dilithium initiators based on 1,3‐bis(1‐ phenylethenyl)benzene. Tetrahydrofuran and lithium sec‐butoxide effects

“…16 The stoichiometric reaction of m-diisopropenylbenzene with two moles of sec-butyllithium has been reported to produce a useful, hydrocarbon-soluble dilithium initiator because of the low ceiling temperature of the m o n~m e r~~~~~ which is analogous in structure to a-methylstyrene; however, other studies suggest that oligomerization occurs with this divinyl compound also and that functionalities higher than two result.27 Higher functionalities have also been reported for the analogous precursor, 1,lbis(4-isopropenylphenyl)-l-phenyltride~ane.~~ A plethora of divinyl aromatic compounds have been evaluated as precursors for hydrocarbonsoluble dilithium initiators' without the emergence of a simple, stable, reproducible initiating system until recent work with 1,3-bis( 1-phenyletheny1)benzene. [29][30][31][32][33][34] The addition reaction of sec-butyllithium with 1,3-bis( 1-phenyletheny1)benzene (eqns (l), (2)) proceeds rapidly and efficiently to produce the corresponding dilithium species with a rate constant for the second addition (k,, eqn (2)) which is equal to the rate constant for the first addition (kl, eqn (1)) in toluene solution,35 but an order of magnitude larger in cy~lohexane.~' It has been reported that this dilithium initiator is not only soluble in hydrocarbon media such as cyclohexane, benzene and toluene (even at -20"C32), but also functions as an efficient difunctional initiator for the preparation of CH, CH, I 1 II 1 2 3 homopolymers and triblock copolymers with relatively narrow molecular weight distribution^.^' -3 1…”

Competitive Processes in Controlled Cationic Ring‐Opening Polymerization of Oxetane: a Lotka‐Volterra Predator‐Prey Model of Two Growing Species Competing for the same Resources

“…Elementary step reactions regulating the pseudo-equilibrium between strain (A1) and non-strain (T1) oxonium tertiary active-chain end species in ''living'' and controlled CROP of oxetane in THP (X ¼ ÀCH ethers in the presence of either ether (diethyl ether,THF,THP,oxepane,1,...) or ester (ethyl acetate, ...) used as additive or (co)solvent. [6] Based on this approach, we recently reported a new synthetic route that allow ''living'' and/or controlled cationic ring-opening polymerization oxetane (Ox) in 1,4-dioxane (1,4-D) and tertahydropyran (THP) (cyclic ethers which have no homopolymerizability) solvent.…”

“…First introduced by Quirk et al in anionic polymerizations, [1] this method has been successfully employed in living carbocationic macromolecular engineering [2][3][4] (i.e. for clean synthesis of blocks (Schemes 1a [2] and 1b [3] ) and end-functionalized (co)polymers (Scheme 2a) [4] as well as in reaction clock method (Scheme 2b) evolve in competitions reactions (i.e.…”

“…polymerizations stop short to completion after one crosspropagation step) for the determination of the structure -reactivity scales of vinylic monomers and corresponding living polymers cations. [5] In those systems, this process involved the quantitative capping reaction of the living polymers with a suitable non-(homo)polymerizable monomer [1][2][3][4] such 1,1-diphenylethylene or 1,1-ditolylethylene (Scheme 1a) followed, i.e. in living cationic sequential block copolymerization by tuning of the Lewis acidity to the reactivity of the second monomer (Scheme 1b).…”